Abstract
The relative effectiveness of altruistic and egocentric persuasion messages is an important research question when voluntary participation in medical research is the target behavior. In the US, most participants in Alzheimer's disease-focused research registries are White females, so increasing diversity in registry membership is a public health priority. We compared the association of two belief-based motivations - egocentric and altruistic - with intention to enroll in an Alzheimer's research registry using a nationally representative theory-based survey of US adults 50 years of age or older while oversampling Black and Hispanic respondents. With the exception of Hispanic females, there were few respondent differences between individual motivational belief items and the correlations between the altruistic and egocentric indices were similar with independent effects on intention: the effects of the two motivations on intention were not redundant. Further analysis demonstrated that a moderation model was not superior to an additive model when both altruistic and egocentric indices simultaneously predicted intention. Registry recruitment messages should use both altruistic and egocentric persuasive message components to increase enrollment into Alzheimer's research registries. Similar studies should determine if the additive effects of altruistic and egocentric motivations apply to other voluntary research participation contexts such as chronic diseases and mental illness.